In this situation, pre- or post-increment doesn't matter. val isn't evaluated until after the incrementing statement. The breakdown of your loop looks like this:

val = 1;
LOOP:
if (val > 10) EXIT FROM LOOP
cout << val << endl; First time through, val is 1.
val++; OR ++val;
// val is now 2, either way. There is no evaluation taking place at this step.
GOTO LOOP
LOOPEXIT

You would need to know which to use if you were evaluating val in that same sequence point. For instance,

val = 1;
if (val++ == 1) // this is true because the comparison is made BEFORE the increment.

val = 1
if (++val == 1) // this is false because the increment is made BEFORE the comparison.